[英]C struct member not storing the value assigned
我正在使用微处理器 (PIC32MX250) 并创建了一个存储各种成员的结构:
typedef struct {
char element1[20];
unsigned char element2;
unsigned char element3[2];
unsigned char element4[2];
unsigned char element5[2];
unsigned char element6[2];
unsigned char element7;
unsigned char element8;
unsigned char element9[2];
unsigned char element10;
unsigned char element11[2];
unsigned char element12;
char element13[7];
unsigned char service_day;
unsigned char service_month;
unsigned char service_year;
unsigned char service_hour;
unsigned char service_minute;
unsigned char service_status[2];
} usb_service_t;
然后我调用 function 读取 flash memory 中的元素并将它们传输到结构中,如下所示:
usb_service_t g_service_container;
void read_service (unsigned int memory_address)
{
byte loop_idx = 0;
byte buf[64] = { 0 };
(void) Flash_Read(memory_address, buf, 64, 0);
g_service_container.service_day= buf[0]; // <<< PROBLEM HERE
g_service_container.service_month= buf[1];
g_service_container.service_year= buf[2];
g_service_container.service_hour= buf[3];
g_service_container.service_minute= buf[4];
for (loop_idx = 0; loop_idx < 20; loop_idx++)
{
g_service_container.targa[loop_idx] = buf[5 + loop_idx];
if (g_service_container.element1[loop_idx] == 0x8e)
{
g_service_container.element1[loop_idx] = 'A';
}
else if (g_service_container.element1[loop_idx] == 0x99)
{
g_service_container.element1[loop_idx] = 'O';
}
else if (g_service_container.element1[loop_idx] == 0x9a)
{
g_service_container.element1[loop_idx] = 'U';
}
}
g_service_container.element1[20] = '\0';
g_service_container.element2= buf[25];
for (loop_idx = 0; loop_idx < 2; loop_idx++)
{
g_service_container.element3[loop_idx] = buf[26 + 1 - loop_idx];
g_service_container.element4[loop_idx] = buf[28 + 1 - loop_idx];
g_service_container.element5[loop_idx] =
buf[30 + 1 - loop_idx];
g_service_container.element6[loop_idx] = buf[32 + 1 - loop_idx];
g_service_container.element9[loop_idx] = buf[36 + 1 - loop_idx];
g_service_container.service_status[loop_idx] = buf[38 + 1 - loop_idx];
g_service_container.element11[loop_idx] =
buf[41 + 1 - loop_idx];
}
g_service_container.element7= buf[34];
g_service_container.element8= buf[35];
g_service_container.element10= buf[40];
g_service_container.element12= buf[43];
for (loop_idx = 0; loop_idx < 7; loop_idx++)
{
g_service_container.element13[loop_idx] = buf[44 + loop_idx];
}
g_service_container.element13[7] = '\0';
}
当我将缓冲区中的元素分配给结构的成员时,我可以通过 MPLAB 调试器看到g_service_container.service_day
始终为 0,特别是buf[0]
不为零(其他读取缓冲区值)。
我试图强制成员的值写入一个常量值并接受它。
然而,以不同的方式编写结构,如下所示,它可以工作:
typedef struct {
char element1[20];
unsigned char element2;
unsigned char element3[2];
unsigned char element4[2];
unsigned char element5[2];
unsigned char element6[2];
unsigned char element7;
unsigned char element8;
unsigned char element9[2];
unsigned char element10;
unsigned char element11[2];
unsigned char element12;
char element13[7];
unsigned char service_status[2]; // NOW I CHANGE THE ORDER OF THIS MEMBER
unsigned char service_day;
unsigned char service_month;
unsigned char service_year;
unsigned char service_hour;
unsigned char service_minute;
} usb_service_t;
听起来编译器正在填充结构。 请参阅此帖子了解其工作原理: https://stackoverflow.com/a/40642888/9766462
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